1. Field of the Invention
This invention relates generally to methods and apparatus for forming an article on an axially (i.e., laterally) tapered (i.e., radially varying) surface of revolution. In particular embodiments, this invention relates to methods and apparatus for generating strips of material and applying the same to an axially tapered surface of revolution, such as, for example, a frusto-conical or conical surface, or a portion of a torus (i.e., the surface of a toroid), to form a tire component, where such surface varies radially while extending in an axial direction to form an “axially tapered surface”. The taper (i.e., radial variation) may be linear or non-linear. For example, an axially tapered building surface forms a sidewall portion of a tire or tire carcass, which, more specifically may be zone-shaped or frusto-conically-shaped.
2. Description of the Related Art
Various processes exist for forming bands comprising tire articles (or components), such as, for example, tire tread bands. Such processes include a winding process in which strips of material are wound about a substantially cylindrical building surface, such as a tire carcass, to build a cylindrical band or wound article. For example, a tread band may be wound about the cylindrical surface of a tire carcass. Substantially cylindrical is defined to mean that the axially extending outer surface of the cylinder extends axially in a linear or slightly arced path. However, such processes are unable to properly and accurately apply strips of material to a non-cylindrical or axially tapered surface, such as, for example, a frusto-conical or zone-shaped surface, which may form a tire sidewall portion. One issue is that the surface velocity of the axially tapered surface varies across its surface width, whereas the surface velocity of a cylindrical surface is substantially constant across its width. Accordingly, difficulty arises when transferring materials from a cylindrical surface to a non-cylindrical surface, especially when transferring at a higher rate or speed. Further, the material will stretch and even move when being transferred between cylindrical and non-cylindrical surfaces due to the change in surface velocities. Therefore, it may be desirous to provide a process that better facilitates application of strips to an axially tapered surface, such as, for example, the application of sidewall material to a sidewall portion of a tire carcass.
In the prior art, one or more strips may be assembled along the substantially cylindrical surface to form the desired profile during the winding process. Application of each strip includes initially placing the strip manually upon the drum, winding the strip about the drum as desired, and subsequently cutting the strip from a supply source when a sufficient quantity of strip has been applied. A subsequent strip may be applied, which generally requires manual attachment thereof to the drum. Application of a second strip may also require a substitution of supply sources. The overall process provides a discontinuous, inefficient process, wherein interruptions arise when building a tire component band with subsequent strips. Therefore, it may be desired to provide a continuous process, where subsequent strips may be formed and applied automatically, without unnecessary interruption or delay.